360 frost plugs

[dodger1]

Any opinions on pros and cons of brass vs. galvanised frost plugs? I just found out I have a corroded (galvanised) one and of course it's right behind the driver side motor mount and can't be changed without lifting the engine. So since the engine was scheduled to come out this winter anyway, I'm gonna change all of them. I understand brass won't corrode from the inside so why don't we find them as OEM?

[70AARCuda]

you can get the brass for a few bucks more for the whole set...


I have yet to have a brass freeze plug corrode

[Rob-D]

Brass soft plugs are normally intended for Marine applications but after pulling the trans and flex plate in my truck to replace a leaking plug I am going with them next time.

[dwc43]

Brass is the only way to go. Will lawst forever.

[dodger1]

Thanks, folks; brass it is!

[pishta]

Yeah, brass is a no brainer. If you have to have steel, paint the back with RTV and let it cure before driving it home.

[George G. Leverette]

If I lived in the cold country I would be thinking of a block heater. The block heater fits in the standard cyclinder block core plug location, the engine would be at operating temperature before it was even started. The engine heaters are still available throught the dealers accessory catlogs.

[dodger1]

George, I probably will include a block heater as well as replace all the other plugs with brass while the mill is out of the car. There's no shortage of them in the parts stores up here, that's for sure.

[dwc43]

Originally Posted by pishta

If you have to have steel, paint the back with RTV and let it cure before driving it home.

DO NOT put RTV on the back of the core plug trying to prevent corrosion. The RTV will flake off in chunks and block the rad over time. SAme reason you use it sparingly on engine builds so it does not end up stopping up the oil pick screen.

If you want to use steel and try to prevent corrosion paint them with electric motor paint. Get it from any place that rebuilds alt.,starters, elec. motors, etc.etc. That stuff wont come off. Same paint racers use on the lifter galley to slick it up so oil runs returns faster to the oil pan.

[dodger1]

That paint is called Glyptal, IIRC, and yes it works very well in oily hot environments, just be sure the surface is prepped right. As for sealant, I'm told a very thin coat of RTV around the edge is OK, but I agree with dwc, I don't want any little bits of that stuff floating around and potentially interfering with a thermostat or plugging rad tubes.

[rr69half6bbl]

yup, dwc is so right on the rtv plugging the pick screen thing, i built a 440 w/windage tray and the oil press. dropped, and couldnt get any from that point, the oil pump had failed, there was a piece of black rtv in the oil pump body. just a small one.
And I cant count the number of times that removing radiators or hoses from cars when i would flush them out where SEVERAL small chunks of gasket sealer would come roling out of the rad.

[Dick]

I read on an old Imperial site that it is OK to use brass in the two end holes, but steel should be used in the middle to act as a corrosion "test" piece. The idea is that the center plug can be pulled from time to time and checked for corrosion on the back side. (That sounds like fun.) This will give you an idea of what is happening in your cooling system.

BTW, the term "freeze plug" or "frost plug" is somewhat incorrect. The proper term is "core plug". These plugs cover the holes that were necessary to have when the block was cast. They allowed the sand to be cleaned out after casting. The fact that the plugs will pop out if the block freezes is secondary.

Kind of like that favorite term "kickdown linkage" which is actually "throttle pressure linkage".....................and that war cannot be won.

[dwc43]

I've got a magnum 318 block in the shop floor with both sides of it cracked from freezing earlier this year. I can promise you the core plugs nine out of ten times wont pop out when the water freezes inside the block.

[Dick]

Originally Posted by dwc43

I've got a magnum 318 block in the shop floor with both sides of it cracked from frezzing earlier this year. I can promise you the core plugs nine out of ten times wont pop out when the water freezes inside the block.

I didn't bring that up, but you are right. Any pressure from ice is going to push in all directions in the water jacket, not just conveniently against the plug. I would bet that very few people have ever had a hard freeze on an engine block.

The plugs are sort of like the turkey timer on a Butterball turkey. When it pops, it's done.

[dodger1]

Well, I know they are core plugs, but after hearing "freeze plugs" for 40 years up here in the cold country, it's kinda hard to get out of the habit. And yes, they won't protect the block from a hard freeze, as mentioned.

[pishta]

Originally Posted by dwc43

DO NOT put RTV on the back of the core plug trying to prevent corrosion. The RTV will flake off in chunks and block the rad over time. SAme reason you use it sparingly on engine builds so it does not end up stopping up the oil pick screen.

If you want to use steel and try to prevent corrosion paint them with electric motor paint. Get it from any place that rebuilds alt.,starters, elec. motors, etc.etc. That stuff wont come off. Same paint racers use on the lifter galley to slick it up so oil runs returns faster to the oil pan.

I guess Ill never do that, I heard it from an old mechanic that probably had a model T in the back. Glad someone straightened that out.

[dwc43]

Welcome,anytime. I'd hate to get someones rad stopped up and then get another thread started on cooling issues that always turns into a war ... lol!!